Adhesives are widely used for securing a variety of articles to substrate(s). Pressure sensitive adhesives (PSA's), in particular, have been widely studied in an attempt to tailor their properties so that they readily “wet out” and bond rapidly to a given surface upon application of minimal pressure. Often, the goal is that articles carrying these adhesives eventually debond, with equal ease, from an underlying surface cleanly, i.e. without leaving any residue behind from either cohesive and/or facestock-adhesive interfacial failures. This objective entails balancing a number of seemingly contradictory properties at the adhesive interface including (i) optimizing the viscoelastic performance window of the adhesive, (ii) assessing the chemistry and solubility parameters of the adhesive components involved and whether they are single or multi-phase separated in nature, (iii) determining the extent of appropriate crosslinking, (iv) considering the conditions of bonding, e.g. pressure, surface roughness, etc, (v) assessing the application and dwell conditions of the adhesive, e.g. contact area and time, temperature, pressure, environmental conditions, etc., and (vi) addressing debonding modes between the adhesive and substrate, e.g. peel angle, speed, environmental conditions, etc.
Although adhesive debonding has been widely discussed and recognized to be an important challenge, few solutions have been achieved. The challenges associated with adhesive debonding are well recognized, as noted in “Pain at Wound Dressing Changes”, C. J. Moffatt, P. J. Franks, H. Hollinworth, Position Document, European Wound Management Association (EWMA), London, UK Medical Partnerships Ltd., pages 1-17, 2002. Adhesive debonding and particularly, with ease and on demand, still presents a formidable technological hurdle.
A wide array of medical products are designed to attach securely to skin and to be retained thereto under a range of adverse conditions including contact with water, e.g. as may be encountered during bathing, swimming, etc.; contact with sweat, sebum or other body fluids; adhering to uneven or complex surface(s) associated with the skin or body that deform variably under mechanical stresses; exposure to heat, e.g. as may occur during a sauna; exposure to sunlight or other environmental factors; contact with other liquids such as hot or cold beverages; and/or being subjected to physical stresses resulting from motion such as during exercise. In view of these and other factors, adhesives for medical applications are typically engineered to adhere securely and for extended time periods to skin.
While many commercial products are known that purportedly facilitate removing an adhesively adhered article from a user's skin, there remains a critical and unmet need for ready, painless removal of the article, on demand, and without causing trauma. This need is particularly evident when adhesively adhered products are peeled off from the skin of elderly patients which is typically fragile and thin. In addition, a need exists for readily removable articles that can be used with children, cancer patients specifically those with skin cancer, premature babies that have skin that is not fully developed, those with diseases that have a severe impact on the skin, or sensitive skin.
“Switchable” Adhesives
Adhesives having selectable or “switchable” adhesion characteristics are known in the art. Temperature switchable adhesives utilize crystallizable moieties within the adhesive matrix that provide for temperature sensitive bonding and debonding. Representative examples of these types of adhesives are described in U.S. Pat. Nos. 5,156,911; 5,387,450; and 5,412,035 for example.
More recently, U.S. Pat. No. 7,399,800 describes utilizing appropriately modified tackifiers.
U.S. Pat. No. 6,610,762 describes the use of post UV polymer crosslinking of a pressure sensitive adhesive to reduce peel strength for easy debonding.
U.S. Pat. No. 5,032,637 describes pressure sensitive adhesives that can be inactivated upon exposure to water by using water soluble tackifiers.
U.S. Pat. No. 7,078,582 exploits the utility of elastic deformation to enable easy removal of medical tapes. This approach is similar to that utilized by certain commercially available products containing adhesives known in the art under the designation “Command” adhesives.
Adhesive Removal in Medical Applications
A prime application of selectively releasable or variable adhesion adhesives, is in the medical field. Among the most common techniques for facilitating adhesive removal or debonding involve contacting the adhesive with various readily available fluids such as (i) oils, (ii) solvents such as isopropyl alcohol, acetone, etc. or (iii) an adhesive removal aid such as Uni-Solve available from Smith & Nephew, Niltac™, or Hollister Medical adhesive remover #7731, etc.
U.S. Pat. No. 4,324,595 describes a method for removing tacky adhesives and articles attached using such adhesives, such as pressure sensitive adhesives in bandages, surgical tape and the like. The method involves applying a volatile methylsiloxane fluid to the tacky adhesive and then removing the bandage or tape from the underlying substrate. The '595 patent specifically notes that the methylsiloxane fluid is applied to the articles and allowed to permeate therethrough to reach the adhesive interface.
U.S. Pat. No. 4,867,981 is directed to tape releasing compositions for separating pressure sensitive adhesive tapes or bandages from an underlying surface. The patent describes that upon application of the composition, the fluid permeates through a porous layer (of the tape or bandage) to the adhesive material, “thereby abating the bonding force”.
Although satisfactory in certain regards, frequent issues exist when using such crude methods such as dispensing inconsistent amounts of adhesive removal fluids, poor distribution of the fluid, need for subsequent clean up, collateral damage or stain to adjacent clothing, and potential harm to the injury site by rubbing or application of pressure, etc. Furthermore, artisans have recognized the importance in attempting to balance the chemistry of the ingredients of adhesive removers in order to enable rapid penetration of the adhesive bulk without unduly compromising its cohesive integrity.
Recognizing these and other deficiencies, artisans have continued to attempt to provide improved techniques and compositions enabling selective removal of adhesively adhered articles. Many of these attempts focused on improving the efficacy of the adhesive removal agent.
Specific examples from the patent literature include the following. U.S. Pat. No. 5,336,207 discloses the use of rubbing oxyalkene ether and liquid hydrocarbons to help remove medical adhesives from the skin.
U.S. Pat. No. 5,004,502 describes the use of non-irritating detackifying agents.
US Patent Application Publication 2007/0054821 A1 discloses the utility of tetrahydrofurfuryl acetate for effective removal of medical adhesives. That publication also calls for “rubbing the remover on the surface in order to enhance removal”.
U.S. Pat. No. 6,436,227 discloses the use of soaking a tape for at least two minutes with limonene to remove adhesive bandages.
None of the previously noted art overcomes the inherent inefficiency of the delivery method of the adhesive removal agent. This is particularly critical when dealing with impermeable devices or systems. U.S. Pat. No. 5,803,639 recognizes this hurdle. However, that patent attempts to overcome the challenges associated with delivery of an adhesive removal agent by devising a special scraping tool to peel an adhesively adhered article from its edges, and thereby expose the adhesive. An adhesion reducing fluid is then administered under the article.
Others have devised an array of different devices and articles that purportedly facilitate adhesive debonding. U.S. Pat. No. 5,843,018 describes the use of a disposable sterile emollient carrier device to treat simple and complex cutaneous injuries by utilizing an elongated non-adhesive wrap around various body parts to attach or detach when needed.
U.S. Pat. No. 6,191,338 discloses a bandage design that minimizes pain from pulling hair during bandage removal.
U.S. Pat. No. 7,396,976 describes an easy to peel bandage construction that contains a plurality of pockets or microcapsules of an adhesive-inactivating ingredient. The microcapsules can be ruptured on demand by application of pressure to enable easy peel off. Premature rupturing is a distinct disadvantage of this approach.
3M and Coloplast have commercial products such as Cavilon™ #3343 (also known as No Sting Barrier Film) or Prep Protective Skin Barrier products like Duoderm. However, these products represent attempts to simply pre-coat the skin prior to adhesive contact to minimize trauma and skin erythema. In this regard, see Dealy C., J. Wound Care, 1, 19 (1992).
Many patents describe low trauma adhesive chemistries utilizing hydrogels, hydrocolloids, soft silicone gels, formulations with aiding additives, etc. However, these strategies often result in inadvertently compromising one or more other desirable properties such as maintaining initial adhesion levels, causing undesirable moisture vapor transmission rate(s) (MVTR) and/or oxygen transmission rate(s) (OTR), or resulting in other unwanted characteristics, etc. Since good adhesion and easy debonding are intrinsically conflicting properties, it is difficult to simultaneously achieve both of these aspects. And, it is exceedingly difficult to accomplish both of these objectives without compromise of other important adhesive properties.
Accordingly, despite the numerous and varied attempts of prior artisans, a need remains for a strategy by which an adhesively adhered article may be easily and painlessly removed from a user's skin, without causing trauma and without any detrimental effects upon the adhesive or the article prior to removal. More particularly, a need remains for an article, system, method and materials for achieving this unique feature.